Since, among other reasons, article handling throughput of an article delivering and receiving portion increases when a number of article transfer operations to or from the article delivering and receiving portion are performed in a row by ceiling transport vehicles, the ceiling transport vehicles that need to transfer articles to or from the article delivering and receiving portion end up forming a waiting line, which may result in a traffic congestion of the ceiling transport vehicles on the travel rail. To this end, intermediate racks for temporarily storing articles to be transferred to or from an article delivering and receiving portion are conventionally provided to prevent such congestion among the ceiling transport vehicles. (See, for example, Patent Document 1.)
In the article transport facility disclosed in Patent Document 1, a transport carriage 16 that functions as a ceiling transport vehicle is configured to be able to transfer an article to or from storage shelves 3-1 to 3-8 that function as intermediate racks by vertically moving fingers 164 that function as a grip portion. Traffic congestions of the ceiling transport vehicles can be prevented in the article transport facility disclosed in Patent Document 1 by virtue of the fact that the ceiling transport vehicles transfer articles to or from the intermediate racks; however, the ceiling transport vehicles can transfer articles only to or from the intermediate racks. More particularly, each intermediate rack is located in a position that is between a ceiling transport vehicle and an article delivering and receiving portion, and that is in vertical alignment, or overlaps vertically, with these; thus, an article cannot be directly transferred to the carrying-in port 51a and from the taking-out port 51b that function as article delivering and receiving portions because the intermediate rack is in the way of the grip portion that is being vertical moved. Transfer of articles to or from the article delivering and receiving portion is performed by a transfer device 2. The transfer device 2 includes, among other things, a vertical movement mechanism 23 for vertically moving an article, an extendable and retractable mechanism 24 for moving the article in the lateral direction, and a grip mechanism 25 for gripping the article. The transfer device 2 is displaced in the lateral direction from the locations in which the transport carriage 16, the carrying-in port 51a, and the taking-out port 51b are located as seen along the travel direction of the transport carriage 16, and is configured to be able to transfer an article to or from both the intermediate rack and the article delivering and receiving portion by moving the article in the lateral direction with the extendable and retractable mechanism 24.
As an article transport facility that includes an intermediate rack and that is configured such that a ceiling transport vehicle can transfer an article directly to or from an article delivering and receiving portion, a configuration is known in which two ceiling transport vehicles are arranged one above the other in a location displaced in the lateral direction from an article delivering and receiving portion in a plan view and in which an intermediate rack is provided above the travel rail for the lower ceiling transport vehicle. (See, for example, FIG. 4 in Patent Document 2.)
In the article transport facility of Patent Document 2, by arranging the intermediate rack and the two ceiling transport vehicles such that they are in vertical alignment, or overlap vertically, with one another at positions that are displaced in the lateral direction from the article delivering and receiving portion as seen along the travel direction of the ceiling transport vehicle and by providing the ceiling transport vehicle with lateral movement operation means for moving the grip portion in the lateral direction, the upper ceiling transport vehicle can transfer an article to or from the intermediate rack and can also transfer an article directly to or from the article delivering and receiving portion.